This invention relates to an improved modulator for an anti-skid braking system.
One important class of modern anti-skid systems utilizes a modulator to provide a smoothly varying, continuous brake control signal. An early example of such systems is disclosed in U.S. Pat. No. 3,724,916, issued April 3, 1973 to Edgar A. Hirzel and assigned to the assignee of the present invention. Such anti-skid systems have achieved a high level of commercial success, particularly for use with large jet transports such as the Boeing 727, 737 and 747 aircraft.
The modulators in these anti-skid systems generate a modulated brake control signal as a time integral function of an input signal indicating a braking condition. In one type of modulator, the input signal is an error signal corresponding to the difference between measured wheel velocity and a reference velocity. This error signal is related to the slip velocity of the braked wheel with respect to the pavement. In another type of modulator, the input signal corresponds to measured wheel deceleration. In either case, the modulated brake control signal varies smoothly and continuously as a time integral function of the input signal.
In the past, such modulators have failed to provide an optimal level of flexibility and certain compromises have been necessary to design a modulator which provides the highest level of braking efficiency.